Normally, when a plurality of devices are connected to a network according to the IEEE1394 standard, in order to link those devices when turning the power OFF, the devices or the main device constantly monitors the operating status of the system, and when it is confirmed that each device can be turned OFF, the power to the devices is turned OFF. For example, as shown in FIG. 1, when device A and device B are connected to a network according to the IEEE1394 standard, in order to link the devices when turning the power OFF, device A checks the operating status of the system of device B at set intervals, and when it is confirmed that device B can be turned OFF, the power to device A and device B is turned OFF.
However, in this conventional method, in order to link turning the power OFF, device A must constantly monitor device B, and so there was a problem in that the burden on device A was large, and the processing to link device A and device B became complicated. Here, a STB 1 is taken to be device A and a printer 2 is taken to be device B, and even when the power link when the STB 1 is connected to this printer 2 is taken into consideration, there same complicated processing is necessary.